Anhydride-functional monomers and polymers and reactive compositions prepared from same

ABSTRACT

Anhydride-functional polymerizable monomers having the structure: ##STR1## and polymers and reactive compositions prepared from these monomers are disclosed. The reactive compositions are especially useful in primer and clearcoat/basecoat applications.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention involves novel anhydride-functional polymerizablemonomers and polymers and reactive compositions prepared from thosemonomers. The anhydride-functional monomers have the structure: ##STR2##wherein R is hydrogen or methyl.

This invention also relates to anhydride-functional polymers having anaverage of at least two anhydride groups per molecule and which areobtained by polymerizing, under free radical addition polymerizationconditions, (i) the anhydride-functional monomer of this invention; and(ii) optionally, at least one other unsaturated monomer copolymerizablewith the anhydride-functional monomer.

This invention also relates to novel reactive compositions which utilizethe anhydride-functional polymer. The polymers are useful as corrosionor scale inhibitors, thickeners, dispersants and as reactive agentsand/or crosslinking agents for compounds having functional groups, suchas epoxy, hydroxyl or amine groups, which are reactive with anhydridegroups. The anhydride-functional polymers can, therefore, be utilized ina variety of materials such as plastics, fibers, adhesives, papersizing, inks and, particularly, coating compositions. The reactivecompositions can be reacted at room temperature or force dried attemperatures ranging up to about 350° F. or higher if desired. Whenutilized as reactive crosslinking agents for coatings, theanhydride-functional polymers may be utilized in a variety of coatingapplications, including primers and topcoats as well as clearcoatsand/or basecoats in clearcoat/basecoat compositions. The monomersthemselves can be utilized as crosslinkers, neutralizers, scalepreventatives, thickeners and many other applications.

The coatings typically involve the combination of theanhydride-functional polymer with materials reactive with anhydridessuch as polyepoxides, polyamines, polyols, etc. One preferred curablecoating combination comprises the anhydride-functional polymer and apolyol, preferably a hydroxy-functional polymer, optionally incombination with an epoxide or polyepoxide. Another preferred curablecoating combination comprises the anhydride-functional polymer, anacid-functional compound, an epoxide or polyepoxide, and, optionally, apolyol. All of these combinations provide fast reacting, durablecoatings which minimize the toxicity problems which may be associatedwith other low temperature curing systems.

2. Description of the Prior Art

Unsaturated anhydrides, such as maleic anhydride, and copolymers madefrom maleic anhydride are known in the art. Such anhydride copolymersare heterogeneous with respect to the distribution of anhydride groupsalong the backbone of the polymer due to the abnormal copolymerizationbehavior of maleic anhydride with other monomers, and the acid groupsgenerated from opening these anhydrides by reaction with hydroxyl oramine groups are not highly reactive for further cure reactions, e.g.with epoxy groups, due to steric hindrance arising from the proximity ofthe anhydride ring to the polymer backbone. Such anhydride-functionalpolymers are also relatively viscous and are difficult to utilize incombination with low levels of solvent. Additionally, such polymers mayform dark colored materials when certain base catalysts, such asN-methyl imidazole, are used to accelerate a subsequent reaction of thepolyanhydride with reactive materials such as hydroxy-functionalcompounds.

Coating compositions comprising polyanhydrides and hydroxy-functionalcompounds are known in the art. For example, U.S. Pat. No. 4,946,744teaches clearcoat/basecoat combinations involving (i) a polyanhydride,for example, such as that prepared by copolymerization of maleicanhydride with (meth)acrylic monomers, and (ii) a polyol. U.S. Pat. No.4,871,806 teaches curable compositions comprising a polyanhydride, apolyacid, a polyol and an epoxy-functional compound. U.S. Pat. No.4,374,235 teaches anhydride-functional polymers prepared by thepolymerization of an alkenyl succinic anhydride and a vinyl monomer. Theprior art has not, however, taught polymers obtained by thepolymerization of the novel anhydride monomers of this invention.

BRIEF SUMMARY OF THE INVENTION

This invention involves polymerizable unsaturated monomers havingpendent anhydride functionality. These versatile monomers have a varietyof potential applications due to their combination of reactive sites.Either the anhydride or the unsaturation functionality could be reactedfirst, followed, if desired, by subsequent reaction of the otherfunctionality. For example, the anhydride group could be reacted withhydroxyl groups on an alcohol or polyol to provide a product having oneor more pendent, polymerizable unsaturation sites. Such a product couldbe subsequently polymerized, either with or without additionalcopolymerizable monomers such as styrene or (meth)acrylic monomers, byperoxide initiation or by exposure to high energy radiation such aselectron beam or ultraviolet light. The anhydride-functional monomercould also be hydrolyzed to produce a diacid-functional monomer.

A particularly preferred use for the monomers of this invention involvestheir use in polymers derived by polymerizing the anhydride monomerthrough its unsaturation either as a homopolymer or, preferably, incombination with one or more additional copolymerizable monomers. Theanhydride-functional polymers can be, if desired, fully or partiallyhydrolyzed, or ring opened by e.g. half-ester or half-amide reactions,to produce acid-functional polymers, or they can be directly utilized ascrosslinking agents for materials having an average of at least twofunctional groups per molecule which are reactive with anhydride groups,such as epoxy, hydroxyl or amine functionality.

Therefore, this invention also relates to curable compositions whichcomprise (i) anhydride-functional polymers prepared using the monomersof this invention, and (ii) a compound having an average of at least twofunctional groups per molecule which are reactive with anhydride groups.A particularly preferred curable composition comprises (i) theanhydride-functional polymer and (ii) a hydroxy-functional compoundhaving an average of at least two hydroxyl groups per molecule,optionally in combination with an epoxide or polyepoxide. Anotherpreferred combination comprises (i) the anhydride-functional polymer,(ii) an acid-functional compound having an average of at least two acidgroups per molecule, (iii) an epoxide or polyepoxide, and, optionally,(iv) a hydroxy-functional compound having an average of at least twohydroxyl groups per molecule. Another useful composition comprises (i)the anhydride-functional polymer and (ii) a polyamine compound having anaverage of at least two primary and/or secondary amine groups permolecule. The term "compound" is used in its broadest sense to includemonomers, oligomers and polymers.

Although the curable compositions of this invention can be utilizedwithout solvent in many applications, it is frequently preferred toutilize them in combination with about 5 to about 50% by weight of aninert solvent. It is convenient to provide the curable composition as amulticomponent system which is reactive upon mixing the components.Especially preferred is a two-component system wherein theanhydride-functional polymer and the acid-functional compound, ifutilized, are combined in one package and the epoxy-functional compoundand/or the hydroxy-functional compound provide a second package. The twopackages can then be mixed together to provide the curable compositionimmediately prior to use.

In one preferred application, this invention also relates to coatedsubstrates having a multi-layer decorative and/or protective coatingwhich comprises:

(a) a basecoat comprising a pigmented film-forming polymer; and

(b) a transparent clearcoat comprising a film-forming polymer applied tothe surface of the basecoat composition;

wherein the clearcoat and/or the basecoat comprises the curablecompositions of this invention. The term "film forming polymer" meansany polymeric material that can form a film from evaporation of anycarrier or solvent.

Accordingly, one object of this invention is to provide novelunsaturated anhydride-functional monomers and polymers therefrom.Another object is to provide improved curable compositions havingexcellent reactivity at low temperatures. It is a further object of thisinvention to provide coating compositions which may be utilized asprimers, topcoats or clearcoats and/or basecoats in clearcoat/basecoatcompositions. Another object of this invention is to provide an improvedtwo-package coating composition wherein one package comprises a novelanhydride-functional polymer and, optionally, an acid-functionalcompound and the other package comprises an epoxy-functional compoundand/or a hydroxy-functional compound. Another object of this inventionis to provide coatings having excellent reactivity, durability andcorrosion resistance. A further object of this invention is to provideimproved coating compositions which can be cured at room temperature orforce dried at elevated temperatures. It is also an object of thisinvention to provide curable compositions which are relatively low inviscosity and which can be utilized with reduced amounts of volatileorganic solvents. These and other objects of the invention will becomeapparent from the following discussions.

DETAILED DESCRIPTION OF THE INVENTION

The unsaturated anhydride monomers of this invention can be convenientlyprepared by the reaction of (i) an unsaturated acid derivative havingthe structure: ##STR3## wherein Z is C1, Br or ##STR4## and each R isindividually H or methyl with (ii) malic acid at temperatures ranging upto about 140° C., preferably from about 70° C. to about 95° C.Representative examples of the unsaturated acid derivative are acrylicanhydride, methacrylic anhydride, acryloyl bromide, methacryloylbromide, acryloyl chloride and methacryloyl chloride. Due to cost,reactivity and the generation of fewer byproducts, methacrylic anhydrideis especially preferred as the unsaturated acid derivative. It is usefulto include a polymerization inhibitor, such as butylated hydroxytoluene,t-butyl catechol, phenol hydroquinone, quinone, etc., in the reactionmixture to prevent the polymerization of the acrylic or methacrylicdouble bonds during the manufacture of the monomer. Commerciallyavailable samples of the acrylic or methacrylic anhydride normallyalready contain a small amount of inhibitor and additional inhibitorsmay not be necessary.

The reaction to produce the unsaturated anhydride monomer can beconducted as a multi-step synthesis. In the first step, 0.9 to about1.2, and especially 1.0 to about 1.1, moles of the unsaturated acidderivative are reacted with about 1.0 moles of malic acid attemperatures ranging up to about 140° C., and preferably about 70° C. toabout 95° C. normally in the presence of an inert solvent such as methylethyl ketone, methyl amyl ketone, etc. The initial reaction of theunsaturated acid derivative is primarily with the hydroxyl group of themalic acid to produce the (meth)acryloxy succinic acid. Thisdicarboxylic acid can subsequently be cyclized to produce the(meth)acryloxy succinic anhydride derivative in several ways. Ifdesired, the dicarboxylic acid can be thermally cyclized by heating thedicarboxylic acid at temperatures of at least about 100° C., andtypically ranging between about 120° C. to about 140° C. Alternatively,the dicarboxylic acid can be reacted with at least an equimolar amountof a reactant which will produce a better leaving group than thecarboxylic acid --OH. For example, the dicarboxylic acid can be reactedwith acetic anhydride followed by subsequent displacement of acetic acidupon ring closure. The reaction of the acetic anhydride and thedicarboxylic acid (typically 1 to 5 moles of acetic anhydride would beprovided for each mole of diacid) can typically be conducted attemperatures ranging from about 60° C. to about 120° C., preferably 80°C. to 100° C., for approximately 1 to 2 hours. The reaction isrepresentatively shown below wherein the unsaturated acid derivative ismethacrylic anhydride and the methacryloxy succinic acid product issubsequently cyclized to produce the methacryloxy succinic anhydridederivative by either thermal cyclization or by reaction with aceticanhydride and subsequent ring closure: ##STR5##

The monomer producing reaction can also be conducted as a single-stepsynthesis resulting in the addition of the unsaturation and the ringclosure to produce the anhydride ring. The reaction is representativelyshown below wherein the unsaturated acid derivative which is reactedwith the malic acid is methacrylic anhydride: ##STR6##

Typically, the unsaturated acid derivative and the malic acid, which canbe either an optically active form or the racemic form of the acid, willbe reacted, optionally in the presence of an inert solvent such as aketone, at temperatures of 25° C. to about 140° C., preferably about 70°C. to 95° C., for about 10 minutes to two hours. When acrylic anhydrideor methacrylic anhydride is utilized as the unsaturated acid derivative,the reaction is normally conducted in the presence of an acid catalyst,typically in the range of 0.01 to about 0.2 percent by weight of thetotal amount of malic acid and unsaturated acid derivative. When thesingle-step synthesis is utilized, the reactants are mixed to provide aratio of moles of unsaturated acid derivative to moles of malic acid offrom about 1.9:1.0 to about 4.0:1.0. It is especially preferred to use aratio of moles of unsaturated acid derivative to moles of malic acidbetween 2.0:1.0 to about 3.0:1.0.

Although, it is not our intent to be bound by theory, it is believedthat in the single-step synthesis, the unsaturated acid derivativereacts with the OH substituent and also with one of the carbonyl groupsof the diacid to effect ring closure. Therefore, theoretically a 2:1mole ratio of the unsaturated acid derivative to malic acid is optimumfor the single-step synthesis. One of the unique advantages of thisone-step process is that both the cyclization to produce the succinicanhydride ring and the introduction of the acrylic or methacrylicunsaturation adjacent to the succinic anhydride ring is effected by thesame reactant so that difficult separation and purification ofintermediate products is avoided. Additionally, when the unsaturatedacid derivative is acrylic anhydride or methacrylic anhydride, theacrylic acid or methacrylic acid by-product of the monomer-producingreaction can be recovered by distillation from the final product mixtureand, if desired, utilized in other applications.

Methacrylic anhydride, which is commercially available from Rohm Tech,Inc. of Malden, Mass., and acrylic anhydride, which is commerciallyavailable from Polysciences, Inc. of Warrington, Pa., are especiallypreferred in the practice of this invention. The acryloyl chloride andmethacryloyl chloride can be conveniently prepared by the reaction ofthe corresponding acid and a chlorinating agent such as thionylchloride, as is well known in the art. The bromide materials can beprepared in a similar fashion using brominating agents. Thepolymerization of the novel monomers of this invention either alone orwith other unsaturated copolymerizable monomers, such as (meth)acrylicor styrene monomers, proceeds at excellent yield and provides polymershaving excellent reactivity, flexibility and overall performance. Thereactivity and flexibility are due, at least in part, to the fact thatthe anhydride groups are separated by at least several atoms from thebackbone of the polymer.

1. ANHYDRIDE-FUNCTIONAL POLYMERS

The anhydride-functional polymers which are useful in the practice ofthis invention will have an average of at least two anhydride groups permolecule and are prepared by polymerizing the anhydride monomers andnormally at least one other copolymerizable monomer under free radicaladdition polymerization conditions. The monomers which are copolymerizedwith the anhydride monomer should be free of any functionality whichcould react with the anhydride group during the polymerization. Theanhydride-functional polymers can be conveniently prepared byconventional free radical addition polymerization techniques. Typicallythe polymerization will be conducted in an inert solvent and in thepresence of an initiator, such as a peroxide or azo compound, attemperatures ranging from 35 ° C. to about 200° C., and especially 75 °C. to about 150° C. Representative initiators include di-t-butylperoxide, di-t-amyl peroxide, cumene hydroperoxide, t-butyl peroctoate,azobis(isobutyronitrile) and ethyl 3,3-di(t-amylperoxy)-butyrate.

The anhydride-functional monomers should generally comprise about 5% to100%, by weight of the monomer mixture used to prepare theanhydride-functional polymer. The remaining 0 to 95% by weight of themonomer mixture, will comprise other reactants copolymerizable with theanhydride-functional monomer. An especially preferredanhydride-functional free radical addition polymer comprises the freeradical addition polymerization product of (a) 5 to 60, and especially15 to about 40, weight percent of the anhydride monomer; and (b) 40 to95, and especially 60 to about 85, weight percent of at least one otherunsaturated monomer copolymerizable with the anhydride monomer.

Representative useful copolymerizable (meth)acrylic monomers includemethyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate,butyl acrylate, isobutyl acrylate, ethyl hexyl acrylate, amyl acrylate,3,5,5 -trimethylhexyl acrylate, methyl methacrylate, ethyl methacrylate,propyl methacrylate, isobornyl methacrylate, lauryl methacrylate,acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile,acrylamide and methacrylamide.

Other monomers which are free of (meth)acrylic functionality which couldalso be used in the polymers of this invention include vinyl acetate,vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl benzoate,vinyl m-chlorobenzoate, vinyl p-methoxy benzoate, vinyl chloride,styrene, alpha-methyl styrene, maleic anhydride, etc.

2. ACID-FUNCTIONAL COMPOUNDS

The acid-functional compounds which, optionally, can be used incombination with the anhydride-functional polymers of this invention inpreparing curable compositions should have an average of at least twocarboxylic acid groups per molecule. Although low molecular weightdiacids and polyacids such as phthalic acid, succinic acid, adipic acid,azelaic acid, maleic acid, fumaric acid, trimellitic acid and trimesicacid can be utilized in combination with the anhydride-functionalpolymers in the practice of this invention, it is especially preferredto utilize polymeric acid-functional compounds.

Preferably the acid-functional polymer will have a number averagemolecular weight of at least about 400. Typical number average molecularweights of the carboxylic acid-functional polymers will range from about500 to about 30,000. Representative acid-functional polymers includeacrylics, polyesters and polymers prepared by the reaction of anhydrideswith hydroxy-functional polymers as discussed more fully below.

2.A. Carboxylic acid-functional polymers prepared by the half-esterforming reaction of anhydrides and hydroxy-functional polymers.

Especially preferred as acid-functional compounds in the curablecompositions of this invention are the carboxylic acid-functionalpolymers prepared by the half-ester opening of the cyclic anhydride byreaction with a hydroxyl group on the hydroxy-functional polymer to formone ester group and one acid group.

Typically, the hydroxy-functional polymers will have number averagemolecular weights of at least about 400 and typical number averagemolecular weights will range from about 400 to about 30,000, andespecially 1,000 to about 15,000. Methods of preparinghydroxy-functional polymers are well known in the art and the method ofpreparation of the hydroxy-functional molecule or polymer which isreacted with the cyclic carboxylic anhydride to produce the optionalacid-functional polymer is not critical to the practice of thisinvention. Representative polymers which can be reacted with anhydridesto produce the acid-functional polymers include the hydroxy-functionalpolyethers, polyesters, acrylics, polyurethanes, polycaprolactones, etc.as generally discussed in Sections 2.A. 1. through 2.A.5. below.

2.A. 1. Polyether polyols are well known in the art and are convenientlyprepared by the reaction of a diol or polyol with the correspondingalkylene oxide. These materials are commercially available and may beprepared by a known process such as, for example, the processesdescribed in Encyclopedia of Chemical Technology, Volume 7, pages257-262, published by Interscience Publishers, Inc., 1951; and inKirk-Othmer Encyclopedia of Chemical Technology, Volume 18, pages638-641, published by Wiley-International, 1982. Representative examplesinclude the polypropylene ether glycols and polyethylene ether glycolssuch as those marketed as Niax® Polyols from Union Carbide Corporation.

2.A.2. Another useful class of hydroxy-functional polymers are thoseprepared by condensation polymerization reaction techniques as are wellknown in the art. Representative condensation polymerization reactionsinclude polyesters prepared by the condensation of polyhydric alcoholsand polycarboxylic acids or anhydrides, with or without the inclusion ofdrying oil, semi-drying oil, or non-drying oil fatty acids. By adjustingthe stoichiometry of the alcohols and the acids while maintaining anexcess of hydroxyl groups, hydroxy-functional polyesters can be readilyproduced to provide a wide range of desired molecular weights andperformance characteristics.

The polyester polyols are derived from one or more aromatic and/oraliphatic polycarboxylic acids, the anhydrides thereof, and one or morealiphatic and/or aromatic polyols. The carboxylic acids include thesaturated and unsaturated polycarboxylic acids and the derivativesthereof, such as maleic acid, fumaric acid, succinic acid, adipic acid,azelaic acid, and dicyclopentadiene dicarboxylic acid. The carboxylicacids also include the aromatic polycarboxylic acids, such as phthalicacid, isophthalic acid, terephthalic acid, etc. Anhydrides such asmaleic anhydride, phthalic anhydride, trimellitic anhydride, or NadicMethyl Anhydride (brand name formethylbicyclo[2.2.1]heptene-2,3-dicarboxylic anhydride isomers) can alsobe used.

Representative saturated and unsaturated polyols which can be reacted instoichiometric excess with the carboxylic acids to producehydroxy-functional polyesters include diols such as ethylene glycol,dipropylene glycol, 2,2,4-trimethyl 1,3-pentanediol, neopentyl glycol,1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol,2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol,2,2-dimethyl-1,3-propanediol, 1,4-cyclohexanedimethanol,1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol,1,4bis(2-hydroxyethoxy)cyclohexane, trimethylene glycol, tetra methyleneglycol, pentamethylene glycol, hexamethylene glycol, decamethyleneglycol, diethylene glycol, triethylene glycol, tetraethylene glycol,norbornylene glycol, 1,4-benzenedimethanol, 1,4-benzenediethanol,2,4-dimethyl-2-ethylenehexane- 1,3-diol, 2-butene- 1,4-diol, and polyolssuch as trimethylolethane, trimethylolpropane, trimethylolhexane,triethylolpropane, 1,2,4-butanetriol, glycerol, pentaerythritol,dipentaerythritol, etc.

Typically, the reaction between the polyols and the polycarboxylic acidsis conducted at about 120° C. to about 200° C. in the presence of anesterification catalyst such as dibutyl tin oxide.

2.A.3. Additionally, hydroxy-functional polymers can be prepared by thering opening reaction of epoxides and/or polyepoxides with primary or,preferably, secondary amines or polyamines to produce hydroxy-functionalpolymers. Representative amines and polyamines include ethanol amine,N-methylethanol amine, dimethyl amine, ethylene diamine, isophoronediamine, etc. Representative polyepoxides include those prepared bycondensing a polyhydric alcohol or polyhydric phenol with anepihalohydrin, such as epichlorohydrin, usually under alkalineconditions. Some of these condensation products are availablecommercially under the designations EPON or DRH from Shell ChemicalCompany, and methods of preparation are representatively taught in U.S.Pat Nos. 2,592,560; 2,582,985 and 2,694,694.

2.A.4. Other useful hydroxy-functional polymers can be prepared by thereaction of an excess of at least one polyol, such as thoserepresentatively described in Section 2.A.2 above, with polyisocyanatesto produce hydroxy-functional urethanes. Representative polyisocyanateshaving two or more isocyanate groups per molecule include the aliphaticcompounds such as ethylene, trimethylene, tetramethylene,pentamethylene, hexamethylene, 1,2-propylene, 1,2-butylene,2,3-butylene, 1,3-butylene, ethylidene and butylidene diisocyanates; thecycloalkylene compounds such as3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate, and the 1,3-cyclopentane, 1,3-cyclohexane, and 1,2-cyclohexane diisocyanates; thearomatic compounds such as m-phenylene, p-phenylene, 4,4'-diphenyl,1,5-naphthalene and 1,4-naphthalene diisocyanates; thealiphatic-aromatic compounds such as 4,4'-diphenylene methane, 2,4 or2,6-toluene, or mixtures thereof, 4,4'-toluidine, and 1,4-xylylenediisocyanates; the nuclear substituted aromatic compounds such asdianisidine diisocyanate, 4,4'-diphenylether diisocyanate andchlorodiphenylene diisocyanate; the triisocyanates such astriphenylmethane-4,4',4"-triisocyanate, 1,3,5-triisocyanate benzene and2,4,6-triisocyanate toluene; and the tetraisocyanates such as4,4'-diphenyl-dimethyl methane-2,2'5,5'-tetraisocyanate; the polymerizedpolyisocyanates such as tolylene diisocyanate dimers and trimers, andother various polyisocyanates containing biuret, urethane, and/orallophanate linkages. The polyisocyanates and the polyols are typicallyreacted at temperatures of 25° C. to about 150° C. to form thehydroxy-functional polymers.

2.A.5. Useful hydroxy-functional polymers can also be convenientlyprepared by free radical polymerization techniques such as in theproduction of acrylic resins. The polymers are typically prepared by theaddition polymerization of one or more monomers. At least one of themonomers will contain, or can be reacted to produce, a reactive hydroxylgroup. Representative hydroxy-functional monomers include 2-hydroxyethylacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate,4-hydroxybutyl methacrylate, 2-hydroxypropyl methacrylate,3-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, 4-hydroxypentylacrylate, 2-hydroxyethyl ethacrylate, 3-hydroxybutyl methacrylate,2-hydroxyethyl chloroacrylate, diethylene glycol methacrylate, tetraethylene glycol acrylate, para-vinyl benzyl alcohol, etc. Typically thehydroxy-functional monomers would be copolymerized with one or moremonomers having ethylenic unsaturation such as:

(i) esters of acrylic, methacrylic, crotonic, tiglic, or otherunsaturated acids such as: methyl acrylate, ethyl acrylate, propylacrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate,ethylhexyl acrylate, amyl acrylate, 3,5,5-trimethylhexyl acrylate,methyl methacrylate, ethyl methacrylate, propyl methacrylate,dimethylaminoethyl methacrylate, isobornyl methacrylate, t-butylmethacrylate, ethyl tiglate, methyl crotonate, ethyl crotonate, etc.;

(ii) vinyl compounds such as vinyl acetate, vinyl propionate, vinylbutyrate, vinyl isobutyrate, vinyl benzoate, vinyl m-chlorobenzoate,vinyl p-methoxybenzoate, vinyl alpha-chloroacetate, vinyl toluene, vinylchloride, etc.;

(iii) styrene-based materials such as styrene, α-methyl styrene, α-ethylstyrene, α-bromo styrene, 2,6-dichlorostyrene, etc.;

(iv) allyl compounds such as allyl chloride, allyl acetate, allylbenzoate, allyl methacrylate, etc.;

(v) other copolymerizable unsaturated monomers such as ethylene,acrylonitrile, methacrylonitrile, dimethyl maleate, isopropenyl acetate,isopropenyl isobutyrate, acrylamide, methacrylamide, and dienes such as1,3-butadiene, etc. The polymers are conveniently prepared byconventional free radical addition polymerization techniques.Frequently, the polymerization will be catalyzed by conventionalinitiators known in the art to generate a free radical such as t-butylperoxyoctoate, t-butyl peroxybenzoate, di-t-butyl peroxide, di-t-amylperoxide, azobis-(isobutyronitrile), cumene hydroperoxide, t-butylperbenzoate, etc. Typically, the acrylic monomers are heated in thepresence of the catalyst at temperatures ranging from about 35° C. toabout 200° C., and especially 75° C. to 150° C., to effect thepolymerization. The molecular weight of the polymer can be controlled,if desired, by the monomer selection, reaction temperature and time,and/or the use of chain transfer agents as is well known in the art.

Especially preferred polymers in the practice of this invention forreaction with the cyclic anhydride to produce the carboxylicacid-functional polymers are hydroxy-functional polyesters andhydroxy-functional acrylic polymers. An especially preferredhydroxy-functional polymer is the addition polymerization reactionproduct of (a) 5 to 100, and especially 10 to about 40, weight percentof a hydroxy-functional ethylenically unsaturated monomer and (b) 0 to95, and especially 60 to about 90, weight percent of at least one otherethylenically unsaturated monomer copolymerizable with thehydroxy-functional monomer.

The cyclic carboxylic acid anhydrides useful in the practice of thisinvention to produce the carboxylic acid-functional half- ester productby reaction with the hydroxy-functional compound can be any monomericaliphatic or aromatic cyclic anhydride having one anhydride group permolecule. Representative anhydrides include phthalic anhydride,3-nitrophthalic anhydride, 4-nitrophthalic anhydride, 3-flourophthalicanhydride, 4-chlorophthalic anhydride, tetrachlorophthalic anhydride,tetrabromophthalic anhydride, tetrahydrophthalic anhydride,hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinicanhydride, dodecenylsuccinic anhydride, octylsuccinic anhydride, maleicanhydride, dichloromaleic anhydride, glutaric anhydride, adipicanhydride, chlorendic anhydride, itaconic anhydride, citraconicanhydride, endo-methylenetetrahydrophthalic anhydride,cyclohexane-1,2-dicarboxylic anhydride, 4-cyclohexene- 1,2dicarboxylicanhydride, 4-methyl-4-cyclohexene- 1,2-dicarboxylic anhydride,5-norbornene-2,3-dicarboxylic anhydride, 1,4-cyclohexadiene-1,2-dicarboxylic anhydride, 1,3-cyclopentanedicarboxylic anhydride,diglycolic acid anhydride, etc. Maleic anhydride is especially preferredbecause of its reactivity and relatively low cost. Other usefulanhydrides include those anhydrides having a free carboxyl group inaddition to the anhydride group such as trimellitic anhydride, aconiticanhydride, 2,6,7-naphthalene tricarboxylic anhydride, 1,2,4-butanetricarboxylic anhydride, 1,3,4-cyclopentane tricarboxylic anhydride,etc.

The reaction of the hydroxy-functional compound and the cyclic anhydridecan be conducted at temperatures ranging up to about 150° C. but shouldnormally be conducted at temperatures less than about 75° C., preferablyless than 65° C., and most preferably between about 35° C. to 60° C. Thereaction temperature is maintained until the reaction has proceeded toprovide the desired amount of half-ester groups on the acid-functionalcompound. Normally, as a convenient measure of the extent of thereaction, the reaction will be continued until no change in the amountof residual unreacted anhydride can be observed, and will generallyinvolve reacting at least about 70%, and preferably at least 95%, of theavailable anhydride. If the subsequent end use of the acid-functionalpolymer can tolerate the remaining free anhydride, if any, no separationor removal of the excess unreacted anhydride is necessary. If the enduse of the acid-functional polymer requires that it be free of anyunreacted anhydride, the reaction can be continued until substantiallyall of the anhydride has reacted, or the free anhydride may be removedby vacuum distillation or other techniques well known in the art.

The level of anhydride reacted with the hydroxy-functional compound needonly be sufficient to provide the final desired acid value of theacid-functional compound. Typically the reaction would be conducted byadmixing the polyol and the anhydride at levels to provide at leastabout 0.3 and normally about 0.7 to 1.0 anhydride groups for eachhydroxyl group. By conducting the reaction at temperatures less thanabout 75° C. the carboxylic acid groups formed as part of the half-esterare not appreciably reactive with the hydroxyl groups themselves and sothey do not compete with the ring opening half-ester reaction of theremaining anhydrides.

In order to conduct the reaction at these relatively low temperatures,it is preferred to utilize an esterification catalyst. The catalystshould be present in sufficient amount to catalyze the reaction andtypically will be present at a level of at least about 0.01%, andnormally from about 0.05% to about 3.0%, based upon the weight of thecyclic anhydride. Catalysts which are useful in the esterificationreaction of the anhydride with the hydroxy-functional molecule includemineral acids such as hydrochloric acid and sulfuric acid; alkali metalhydroxides such as sodium hydroxide; tin compounds such as stannousoctoate, or dibutyltin oxide; aliphatic or aromatic amines, especiallytertiary alkyl amines, such as triethylamine; and aromatic heterocyclicamines such as N-methyl imidazole and the like. Especially preferred areN-methyl imidazole and triethylamine.

Although the reaction between the hydroxy-functional compound and theanhydride can be conducted in the absence of solvent if the materialsare liquid at the reaction temperature, it is normally preferred toconduct the reaction in the presence of an inert solvent such as esters,ketones, ethers or aromatic hydrocarbons. If desired, theacid-functional molecule can be utilized as the solvent solution, or,optionally, all or part of the inert solvent may be removed, e.g. bydistillation, after the reaction is completed.

After the reaction is completed, it is frequently desirable to add a lowmolecular weight alcohol solvent, such as isobutanol or isopropanol, tothe acid-functional compound at a level of about 5 to 35 percent byweight to provide stabilization on storage.

2.B. Carboxylic Acid-Functional Polymers Prepared From UnsaturatedAcid-Functional Monomers

Useful acid-functional polymers can also be conveniently prepared by thefree radical addition polymerization of unsaturated acids such as maleicacid, acrylic acid, methacrylic acid, crotonic acid, etc. along with oneor more unsaturated monomers. Representative monomers include the estersof unsaturated acids, vinyl compounds, styrene-based materials, allylcompounds and other copolymerizable monomers as representatively taughtin Section 2.A.5. of this specification. The monomers which areco-polymerized with the unsaturated acid should be free of anyfunctionality which could react with the acid groups during thepolymerization.

2.C. Carboxylic Acid-Functional Polymers Prepared From Polyols andPolyacids

Other useful acid-functional polymers include polyester polymersobtained from the reaction of one or more aromatic and/or aliphaticcarboxylic acids or their anhydrides and one or more aliphatic and/oraromatic polyols wherein the acid functionality is present in astoichiometric excess over the hydroxy functionality. Representativecarboxylic acids and polyols include those listed in Section 2.A.2. ofthis specification.

3. EPOXY-FUNCTIONAL COMPOUNDS

The curable coatings of this invention may also incorporate at least oneepoxy-functional compound. The epoxy compounds can, if there aresufficient other reactive materials to provide crosslinking, bemonoepoxies or, preferably, a polyepoxide having an average of at leasttwo epoxy groups per molecule.

Representative useful monoepoxides include the monoglycidyl ethers ofaliphatic or aromatic alcohols such as butyl glycidyl ether, octylglycidyl ether, nonyl glycidyl ether, decyl glycidyl ether, dodecylglycidyl ether, p-tert-butylphenyl glycidyl ether, and o-cresyl glycidylether. Monoepoxy esters such as the glycidyl ester of versatic acid(commercially available as CARDURA® E from Shell Chemical Company), orthe glycidyl esters of other acids such as tertiary-nonanoic acid,tertiary-decanoic acid, tertiary-undecanoic acid, etc. are also useful.Similarly, if desired, unsaturated monoepoxy esters such as glycidylacrylate, glycidyl methacrylate or glycidyl laurate could be used.Additionally, monoepoxidized oils can also be used.

Other useful monoepoxies include aryl epoxides such as styrene oxide,and alkene oxides such as cyclohexene oxide, 1,2-butene oxide,2,3-butene oxide, 1,2-pentene oxide, 1,2-heptene oxide, 1,2-octeneoxide, 1,2-nonene oxide, 1,2-decene oxide, and the like.

It is only necessary that the monoepoxide compounds have a sufficientlylow volatility to remain in the coating composition under the applicableconditions of cure.

Polyepoxides are especially preferred in the reactive coatings of thisinvention. Especially preferred as the poly-functional epoxy compounds,due to their reactivity and durability, are the polyepoxy-functionalcycloaliphatic epoxies. Preferably, the cycloaliphatic epoxies will havea number average molecular weight less than about 2,000 to minimize theviscosity. The cycloaliphatic epoxies are conveniently prepared bymethods well known in the art such as epoxidation of dienes or polyenes,or the epoxidation of unsaturated esters by reaction with a peracid suchas peracetic and/or performic acid.

Commercial examples of representative preferred cycloaliphatic epoxiesinclude 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate (e.g."ERL-4221" from Union Carbide Corp. );bis(3,4-epoxycyclohexylmethyl)adipate (e.g. "ERL-4299" from UnionCarbide Corporation);3,4-epoxy-6-methylcyclohexylmethyl3,4-epoxy-6-methylcyclohexanecarboxylate (e.g. "ERL-4201" from Union Carbide Corp. );bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate (e.g. "ERL-4289" fromUnion Carbide Corp.); bis(2,3-epoxycyclopentyl) ether (e.g. "ERL0400"from Union Carbide Corp.); dipentene dioxide (e.g. "ERL-4269" from UnionCarbide Corp.); 2-(3,4-epoxycyclohexyl-5, 5-spiro-3,4-epoxy)cyclohexanemetadioxane (e.g. "ERL-4234" from Union Carbide Corp.). Othercommercially available cycloaliphatic epoxies are available fromCiba-Geigy Corporation such as CY 192, a cycloaliphatic diglycidyl esterepoxy resin having an epoxy equivalent weight of about 154. Themanufacture of representative cycloaliphatic epoxies is taught invarious patents including U.S. Pat. Nos. 2,884,408, 3,027,357 and3,247,144.

Other polyepoxides potentially useful in the practices of this inventioninclude aliphatic and aromatic polyepoxies, such as those prepared bythe reaction of an aliphatic polyol or poly hydric phenol and anepihalohydrin. Other useful epoxies include epoxidized oils andepoxy-functional copolymers such as acrylic polymers derived fromethylenically unsaturated epoxy-functional monomers such as glycidylacrylate or glycidyl methacrylate in combination with othercopolymerizable monomers such as those listed in 2.A.5 above.

4. HYDROXY-FUNCTIONAL COMPOUNDS

The hydroxy-functional compounds which are useful in combination withthe anhydride-functional polymers to prepare curable compositions in thepractice of this invention should have an average of at least twohydroxyl groups per molecule. Although low molecular weight diols andpolyols such as propylene glycol, 1,6 hexanediol, triethanol amine andpentaerythritol can be utilized in the practice of this invention, it isespecially preferred to utilize polymeric hydroxy-functional compoundssuch as polyethers, polyesters, acrylics, polyurethanes,polycaprolactones, etc.

Preferably the hydroxy-functional polymer will have a number averagemolecular weight of at least about 400. Typical number average molecularweights will range from about 400 to about 30,000, and especially 1,000to about 15,000. In order to provide the fastest rate of reaction duringcure it is preferred in the practice of this invention to utilizehydroxy-functional compounds having predominantly, and preferably all,primary hydroxy functionality.

Representative hydroxy-functional polymers are taught in Sections 2.A. 1. through 2.A. 5. Especially preferred as the hydroxy-functionalpolymer is a hydroxy-functional polymer comprising the additionpolymerization reaction product of (a) 10 to about 60 weight percent ofa hydroxy-functional ethylenically unsaturated monomer and (b) 40 toabout 90 weight percent of at least one ethylenically unsaturatedmonomer copolymerizable with the hydroxy-functional monomer.

5. AMINE-FUNCTIONAL COMPOUNDS

Amine-functional compounds which are useful in combination with theanhydride-functional polymers to prepare curable compositions in thepractice of this invention should have an average of at least twoprimary or secondary amine groups per molecule. Polyamines can beprepared by methods well known in the an such as by the free radicalpolymerization of acrylic or other unsaturated monomers having primaryor secondary amine functionality, or by the reaction of amines having atleast two amine groups per molecule with a polycarboxylic acid to formpolyamide amines, or by the reaction of primary amines with epoxymaterials to produce secondary amine and hydroxyl functionality. Thepolyamines can be polymeric, typically having a number average molecularweight over 400, or lower molecular materials, such as piperazine,tetraethylenepentamine, 1,2-diaminopropane, 1,6-diaminohexane, etc. Alsouseful are the materials having a primary or secondary amine group and ahydroxyl group such as isopropanol amine, isobutanol amine, ethanolamine, etc.

The ratios of anhydride to other functional groups in the curablecompositions can be widely varied within the practice of this inventionas long as at least some of each group is present in the reactivecomposition. It is only necessary to combine the anhydride-functionalpolymer and other reactive materials in amounts to provide the desireddegree of crosslinking upon cure. When a combination of theanhydride-functional polymer and a polyol or polyamine is used as thecurable composition, it is preferred to provide about 0.3 to about 10hydroxyl or amine groups for each anhydride group, and especially 1 toabout 5 hydroxyl or amine groups for each anhydride group. When thecurable composition involves a combination of only theanhydride-functional polymer, an epoxide or polyepoxide, and a polyol itis preferred to provide 0.3 to about 6.0 hydroxyl groups, and about 0.3to about 6.0 epoxy groups for each anhydride group, and especially toprovide 0.5 to 2.5 hydroxyl groups and 0.5 to 2.5 epoxy groups for eachanhydride group. When the curable composition involves theanhydride-functional polymer, an acid-functional compound and apolyepoxide, it is preferred to provide 0.3 to 6.0 acid groups and 0.6to 12.0 epoxy groups for each anhydride group, and especially 2.0 toabout 5.0 acid groups and 3.0 to about 8.0 epoxide groups for eachanhydride group. If the reactive curable composition comprises theanhydride-functional polymer, an acid-functional compound, an epoxide orpolyepoxide, and a hydroxy-functional compound, it is preferred toprovide from 0.05 to about 3.0 acid groups and about 0.5 to about 4.0epoxy groups and about 0.05 to 6.0 hydroxyl groups for each anhydridegroup in the reactive system. It is especially preferred to provide 1.0to about 2.0 acid groups and 1.0 to about 3.0 epoxy groups and about 1.0to about 4.0 hydroxyl groups for each anhydride group.

The curable compositions of this invention can be cured at temperaturesranging from about room temperature up to about 350° F. When the curablecompositions are utilized as coatings, the coatings can be clearcoatings or they may contain pigments as is well known in the art.Representative opacifying pigments include white pigments such astitanium dioxide, zinc oxide, antimony oxide, etc. and organic orinorganic chromatic pigments such as iron oxide, carbon black,phthalocyanine blue, etc. The coatings may also contain extenderpigments such as calcium carbonate, clay, silica, talc, etc.

The coatings may also contain other additives such as flow agents,catalysts, diluents, solvents, ultraviolet light absorbers, etc.

It is especially preferred in the curable compositions of this inventionto include a catalyst for the reaction of anhydride groups and hydroxylgroups and/or a catalyst for the reaction of epoxy and acid groups ifpresent in the curable compositions. It is especially preferred in thepractice of this invention to utilize tertiary amines and especiallyN-methylimidazole as a catalyst for the anhydride/hydroxyl reaction. Thecatalyst for the anhydride/hydroxyl reaction will typically be presentat a level of at least 0.01% by weight of the anhydride compound andpreferably 1.0 to about 5.0%.

Tertiary amines, secondary amines such as ethyl imidazole, quaternaryammonium salts, nucleophilic catalysts, such as lithium iodide,phosphonium salts, and phosphines such as triphenyl phosphine areespecially useful as catalysts for epoxy/acid reactions. The catalystfor the epoxy/acid reaction will typically be present at a level of atleast 0.01% by weight of the total acid-functional compound andepoxy-functional compound and will preferably be present at 0.1 to about3.0%.

Since the curable compositions of this invention are typically providedas multi-package systems which must be mixed together prior to use, thepigments, catalysts and other additives can be conveniently added to anyor all of the appropriate individual packages.

The curable compositions may typically be applied to any substrate suchas metal, plastic, wood, glass, synthetic fibers, etc. by brushing,dipping, roll coating, flow coating, spraying or other methodconventionally employed in the coating industry.

One preferred application of the curable coatings of this inventionrelates to their use as clearcoats and/or basecoats inclearcoat/basecoat formulations.

Clearcoat/basecoat systems are well known, especially in the automobileindustry where it is especially useful to apply a pigmented basecoat,which may contain metallic pigments, to a substrate followed by theapplication of a clearcoat which will not mix with or have anyappreciable solvent attack upon the previously applied basecoat.Typically, at least some of the solvent will be allowed to evaporatefrom the basecoat prior to the application of the clearcoat. In someapplications the basecoat may even be allowed to cure, at leastpartially, prior to application of the clearcoat. The basecoatcomposition may be any of the polymers known to be useful in coatingcompositions including the reactive compositions of this invention.

One useful polymer basecoat includes the acrylic addition polymers,particularly polymers or copolymers of one or more alkyl esters ofacrylic acid or methacrylic acid, optionally together with one or moreother ethylenically unsaturated monomers. These polymers may be ofeither the thermoplastic type or the thermosetting, crosslinking typewhich contain hydroxyl or amine or other reactive functionality whichcan be crosslinked. Suitable acrylic esters for either type of polymerinclude methyl methacrylate, ethyl methacrylate, propyl methacrylate,butyl methacrylate, ethyl acrylate, butyl acrylate, vinyl acetate,acrylonitrile, acrylamide, etc. Where the polymers are required to be ofthe crosslinking type, suitable functional monomers which can be used inaddition to those already mentioned include acrylic or methacrylic acid,hydroxy ethyl acrylate, 2-hydroxy propyl methacrylate, glycidylacrylate, tertiary-butyl amino ethyl methacrylate, etc. The basecoatcomposition may, in such a case, also contain a crosslinking agent suchas a carbodiimide, a polyanhydride, a polyisocyanate a polyepoxide, or anitrogen resin such as a condensate of an aldehyde such as formaldehydewith a nitrogenous compound such as urea, melamine or benzoguanamine ora lower alkyl ether of such a condensate. Other polymers useful in thebasecoat composition include vinyl copolymers such as copolymers ofvinyl esters of inorganic or organic acids, such as vinyl chloride,vinyl acetate, vinyl propionate, etc., which copolymers may optionallybe partially hydrolyzed so as to introduce vinyl alcohol units.

Other polymers useful in the manufacture of the basecoat include alkylresins or polyesters which can be prepared in a known manner by thecondensation of polyhydric alcohols and polycarboxylic acids, with orwithout the inclusion of natural drying oil fatty acids as describedelsewhere in this specification. The polyesters or alkyds may contain aproportion of free hydroxyl and/or carboxyl groups which are availablefor reaction, if desired with suitable crosslinking agents as discussedabove.

If desired, the basecoat composition may also contain waxes, rheologymodifiers, cellulose esters, or other additives to alter the appearance,drying or viscosity characteristics of the basecoat.

Typically, the basecoat will include pigments conventionally used forcoating compositions and after being applied to a substrate, which mayor may not previously have been primed, the basecoat will normally beallowed sufficient time to form a wet polymer film which will not belifted during the application of the clearcoat. The clearcoat is thenapplied to the surface of the basecoat, and the system can be allowed todry or, if desired, can be force dried by baking the coated substrate attemperatures typically ranging up to about 250° F.

Typically, the clearcoat may contain ultraviolet light absorbers orstabilizers, such as hindered phenols or hindered amines at a levelranging up to about 6% by weight of the vehicle solids as is well knownin the art. The clearcoat can be applied by any application method knownin the art, but preferably will be spray applied. If desired, multiplelayers of basecoat and/or clearcoat can be applied. Typically, both thebasecoat and the clearcoat will each be applied to give a dry filmthickness of about 0.01 to about 6.0, and especially about 0.5 to about3.0 mils.

The following examples have been selected to illustrate specificembodiments and practices of advantage to a more complete understandingof the invention. Unless otherwise stated, "parts" means parts-by-weightand "percent" is percent-by-weight.

EXAMPLE A

A reaction vessel fitted with a temperature control device, a stirringbar, a condenser, a drying tube and a heating mantle was charged with amixture of 36 parts methacrylic anhydride, 13.4 parts DL-malic acid, and0.05 parts concentrated sulfuric acid. The mixture was stirred at roomtemperature for 1 hour and then the reaction temperature was kept at 80°C. for an additional hour. The product mixture was cooled and vacuumdistilled at room temperature for 10 minutes followed by vacuumdistillation by a rotary evaporator at 80° C. for 10 minutes and 100° C.for an additional 10 minutes to remove excess methacrylic anhydride andby-products. The residue from the distillation was crystallized fromanhydrous ether and vacuum dried overnight. The product, which wasproduced in approximately 92% yield, was identified by both FT infraredand NMR to be the desired (2-succinic anhydride)methacrylate (theproduct could alternatively be named 2-(methacryloxy)-succinicanhydride).

EXAMPLE B

A reaction vessel equipped as described in Example A was charged with amixture of 32.8 parts methacrylic anhydride, 13.5 parts DL-malic acidand 0.05 parts concentrated sulfuric acid. The reaction mixture washeated to 80° C. from room temperature in approximately 10 minutes atwhich point the heating was stopped and the reaction continued toexotherm to about 85° C. The heterogeneous mixture became a clearsolution at 85 ° C. and was allowed to cool to room temperature and 0.01parts butylated hydroxy toluene was added to the mixture. The productmixture was vacuum distilled to remove unreacted methacrylic anhydrideand by-products, and the reaction product was worked up as described inExample A. The product was identified by FT infrared to be the desired(2-succinic anhydride) methacrylate.

EXAMPLE C

A reaction vessel equipped as described in Example A was charged with amixture of 13.4 parts DL-malic acid and 29.0 parts methacryloylchloride. The reaction mixture was heated to 80° C. with stirring whileunder a nitrogen purge. Within approximately 1 hour 20 minutes theheterogeneous mixture had become a red solution which was vacuumdistilled at 50° C. for 15 minutes and 100° C. for 5 minutes to yield aresidue which contained primarily the desired (2-succinicanhydride)methacrylate.

EXAMPLE 1

A reaction vessel equipped with a stirring bar, a heat controller and adropping funnel was charged with 23 parts methyl isobutyl ketone andheated to 100° C. under nitrogen purge. A solution of 9.2 parts of(2-succinic anhydride)methacrylate, 9.2 parts butyl acrylate, 4.6 partsstyrene, and 1.38 parts t-butyl peroctoate was added dropwise to theheated solvent solution over 21/2 hours. The temperature was raised to110° C. approximately 40 minutes after the initiation of the reactionand the reaction was maintained at that temperature for approximately1/2 hour after the monomer addition was completed. The final transparentanhydride-functional polymer had a number average molecular weight ofapproximately 3,500 (relative to polystyrene standard), a polydispersityof 2.0, an observed glass transition temperature of 52.1° C., a densityof approximately 8.05 lbs/gallon, and a Brookfield viscosity ofapproximately 200 centipoise at a percent weight solids (NVM) of 52.9%.

EXAMPLE 2

A reaction vessel equipped as described in Example 1 was charged with 83parts methyl amylketone and heated to 100° C. A solution of 75 parts of(2-succinic anhydride)methacrylate, 100 parts butyl acrylate, 25 partsbutyl methacrylate, 25 parts styrene, 25 parts methyl methacrylate, and20 parts t-butyl peroctoate was added dropwise to the heated solutionover 2 hours. The reaction temperature was then held at 100° C. for 1/2hour after completing the addition of the entire monomer mixture. Anadditional 2.5 parts of t-butyl peroctoate was added and the reactionmixture was maintained at 100° C. for an additional 1/2 hour. The finaltransparent anhydride-functional polymer was 71.6% NVIVI by the andexhibited a density of 8.51 lbs/gallon, a number average molecularweight of approximately 4,400 (relative to polystyrene standard), apolydispersity of 3.1 and an observed glass transition temperature of31.3° C.

EXAMPLE 3

A reaction vessel equipped as described in Example 1 was charged with167 parts Dowanol® PM acetate (propylene glycol monomethyl ether acetatecommercially available from Dow Chemical Company) and heated to 115° C.A solution of 225 parts butyl acrylate, 50 parts butyl methacrylate, 150parts (2-succinic anhydride)methacrylate, 50 parts styrene, 25 partsmethacrylic acid, and 40 parts t-butyl peroctoate was added dropwise tothe heated solution over a 3 hour period. The reaction temperature wasthen held at 115° C. for an additional 1/2 hour after completing theaddition of the entire monomer mixture. An additional 5.0 pans oft-butyl peroctoate in 47 parts methyl amyl ketone was added to thereaction mixture and maintained at that temperature for approximately1/2 hour. The final transparent anhydride-functional polymer had an NVMof 72%, a number average molecular weight of approximately 4,500(relative to polystyrene standard), a polydispersity of 2.9, aBrookfield viscosity of 404 poise and an observed glass transitiontemperature of 31.6° C.

EXAMPLE 4

A clear curable composition, suitable for use as a clearcoat inclearcoat/basecoat coating applications, was prepared by admixing theanhydride-functional resin of Example 1 and Tone® 305 (polycaprolactonetriol commercially available from Union Carbide Corporation having amolecular weight of about 540 and a hydroxyl equivalent weight of about180) at a ratio to provide one anhydride group per each hydroxy group.Approximately 1% of N-methylirnidazole based upon anhydride resin solidswas added to the mixture as catalyst and the curable composition wasapplied to a steel substrate and allowed to dry at room temperature. Thecurable composition gave good hardness and resistance to methyl ethylketone.

EXAMPLE 5

A clear curable composition suitable for use as a clearcoat in aclearcoat/basecoat coating composition, was prepared by mixing at aratio to provide one epoxy group and one hydroxy group for eachanhydride group, the anhydride-functional polymer of Example 1, Tone®305, and ERL-4229 (cycloaliphatic diepoxide commercially available fromUnion Carbide Corporation). The curable composition was applied to asteel substrate and allowed to dry at room temperature to give a hardcured film having good resistance to methyl ethyl ketone.

EXAMPLE 6

A curable composition was prepared by admixing the anhydride-functionalpolymer of Example 3, a hydroxy-functional acrylic polymer, and epoxyresin ERL-4299 in amounts to provide an equivalent ratio of anhydridegroups to hydroxyl groups to epoxy groups of 2/1/2. The clearcoatcomposition was catalyzed with N-methylimidazole at 0.1% weight solidsbased on total reactive resin solids. The clearcoat was spray appliedover Q-steel panels coated with a commercial primer, commercial sealerand a commercial basecoat and allowed to air dry at ambient roomtemperature. The clearcoat dried to a hard film overnight and showedgood resistance to methyl ethyl ketone and good hardness.

The hydroxy-functional polymer had been prepared by initially charging areaction vessel equipped with a mechanical stirrer, a water-cooledcondenser, nitrogen inlet, thermometer, heating mantle and fluidmetering pump with 1,700 parts of xylene. The xylene was heated to 135°C. and a monomer mixture composed of 970 parts styrene, 320 parts methylmethacrylate, 710 parts Tone® M100 (trademark of Union Carbide'shydroxy-functional acrylic caprolactone adduct believed to be thereaction product of 1 mole of hydroxymethyl acrylate and 2 moles ofcaprolactone), 190 parts hydroxyethyl acrylate, 390 parts butyl acrylateand 253 parts of t-butyl peroctoate was metered into the reactionmixture over approximately 3 hours. Three individual additions of 10.7parts xylene and 2.6 parts t-butyl peroctoate were added to the reactionmixture at approximately 15 minutes, 30 minutes and 45 minutes after thecompletion of the monomer addition. The reaction temperature was thenmaintained at 130° C. for 2 hours. The resulting hydroxy-functionalacrylic polymer had a number average molecular weight of approximately3,000 (relative to polystyrene standard), a poly-dispersity ofapproximately 3.0, a Brookfield viscosity of 2.9 poise at an NVM of 59%and a density of 8.29 pounds per gallon.

Other reactive systems, such as the combination of apolyepoxy-functional material, an acid-functional material and theanhydride-functional polymer of this invention are also practical, andcould, optionally, also incorporate hydroxy-functional materials aswell.

While this invention has been described by a specific number ofembodiments, other variations and modifications may be made withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

The entire disclosure of all applications, patents and publicationscited herein are hereby incorporated by reference.

The invention claimed is:
 1. An anhydride-functional monomer having thestructure: ##STR7## wherein R is hydrogen or methyl.
 2. The monomer ofclaim 1 wherein R is methyl.
 3. The monomer of claim 1 wherein R ishydrogen.